> Australia had big problems with over-supply of solar at certain times and I believe the rate went negative to try and stop people feeding it in.
This is almost certaintly untrue, in both the wider and narrow senses.
Basically, solar alone will never cause negative prices or 'oversupply', because solar can switch itself off fast enough that any solar bidding a negative price to the market would just turn itself off rather than pay money to someone who uses the power. The same is true of wind turbines.
Because you reference Australia, it was almost certainly coal plants that were bidding negative because it would cost them more to ramp down and back up again as demand changes.
There's some incentive regimes, that can lead to renewables offering to pay people to take their power (if they get paid $X for each used watt, then they can pass some of that subsidy on to a user rather than stop providing) but that's a good thing, not a bad thing. It's just a price signal that rewards flexible demand.
In the words of an Australian coal energy producer:
https://www.stanwell.com/our-news/energy-explainer/negative-...
> Negative prices are a signal to either increase demand or reduce supply. Intermittent and fast response energy sources (such as solar, wind, peaking generators) can stop and start in relatively short spaces of time to avoid negative price periods. Coal-fired generators however, incur significant costs stopping and starting and require many hours to restart. This means they continue generating throughout negative pricing periods as it is more cost-efficient to incur the costs of negative pricing than shutting down and then starting up again. This ensures that they are available to meet peak demand in the late afternoon and evening once the intermittent sources such as rooftop solar and large-scale solar are no longer available.
This is almost certaintly untrue, in both the wider and narrow senses.
Basically, solar alone will never cause negative prices or 'oversupply', because solar can switch itself off fast enough that any solar bidding a negative price to the market would just turn itself off rather than pay money to someone who uses the power. The same is true of wind turbines.
Because you reference Australia, it was almost certainly coal plants that were bidding negative because it would cost them more to ramp down and back up again as demand changes.
There's some incentive regimes, that can lead to renewables offering to pay people to take their power (if they get paid $X for each used watt, then they can pass some of that subsidy on to a user rather than stop providing) but that's a good thing, not a bad thing. It's just a price signal that rewards flexible demand.
In the words of an Australian coal energy producer:
https://www.stanwell.com/our-news/energy-explainer/negative-...
> Negative prices are a signal to either increase demand or reduce supply. Intermittent and fast response energy sources (such as solar, wind, peaking generators) can stop and start in relatively short spaces of time to avoid negative price periods. Coal-fired generators however, incur significant costs stopping and starting and require many hours to restart. This means they continue generating throughout negative pricing periods as it is more cost-efficient to incur the costs of negative pricing than shutting down and then starting up again. This ensures that they are available to meet peak demand in the late afternoon and evening once the intermittent sources such as rooftop solar and large-scale solar are no longer available.